I am not sure that when I do wudu I get water on all of my skin. Particularly, the heel areas of my feet. I do my best to go over every groove but I'm not sure if I unintentionally left a spot dry.
I don't know what to do in this case...again I'm not 100% sure that every portion got wet, but do I just assume that they did? I'm worried now that my past salats may be invalid.